Structure for positioning a watch stem

ABSTRACT

A watch stem having annular grooves thereon is precisely positioned by means of a leaf spring held at one end to a base plate. Proximate the other end of the leaf spring a tab bent toward the base plate seats in one of the annular grooves. Second and third tabs span the watch stem in a diametral direction and prevent motion of the watch stem in a direction transverse to the axis. A fourth tab is positioned by the walls of a notch in a member fastened to the base plate. The leaf spring is thereby prevented from moving in a direction parallel to the axis of the stem.

United States Patent Miyasaka et a1.

STRUCTURE FOR POSITIONING A WATCH STEM Inventors: Mamoru Miyasaka; Hiroh'sa Kurita;

Hideo Furihata, all of Shimosuwa-Machi Appl. No.: 166,798

Foreign Application Priority Data July 31, 1970 Japan ..45/66508 U.S. (I 8/58, 58/99 Int. Cl ..G04b 19/24, G04b 37/06 Field of Search ..58/58, 95-99 References Cited UNITED STATES PATENTS Matalene ..5 8/99 51 July 25,1972

Primary Examiner--Richard B. Wilkinson Assistant Examiner-George H. Miller, Jr. Attorney-Alex Friedman et a1.

[57] ABSTRACT A watch stem having annular grooves thereon is precisely positioned by means of a leaf spring held at one end to a base plate. Proximate the other end of the leaf spring a tab bent toward the base plate seats in one of the annular grooves. Second and third tabs span the watch stem in a diametral direction and prevent motion of the watch stem in a direction transverse to the axis. A fourth tab is positioned by the walls of a notch in a member fastened to the base plate. The leaf spring is thereby prevented from moving in a direction parallel to the axis of the stem.

2 Claims, 3 Drawing Figures Patented July 25, 1972 FIG. 2

INVENTORS. MAMQRU MIYASAKA Y HIROHISA KURlTA HIDEO FURIHATA 6- %aa-40mrm A TTORNEYS STRUCTURE FOR POSITIONING A WATCH STEM BACKGROUND OF THE INVENTION In a conventional mechanism for locating the watch stem in a watch, a pinch a setting lever is engaged with a groove on the stem and the radial position is determined by the base plate of the mechanism. Such mechanisms have the following defects:

1. The clearance of the stem in axial and radial directions is comparatively large.

2. Since the setting lever is positioned by the shape and position of a spring lever, the axial position of the stem may vary.

3. The length of the inward and outward strokes used in the positioning of the watch stem varies to an unacceptable extent.

4. The pressing operation in the formation of the setting lever pin is complex.

5. The number of parts required and the space required are both large. 1

6. The construction is such that it is difficult to obtain high precision either in the manufacture or in the operation.

SUMMARY OF THE INVENTION Positioning of a watch stem axially in any of a plurality of positions is achieved by means of annular grooves thereon and a leaf spring fastened to a base plate. The leaf spring has a bent-down tab which can seatin any of the annular grooves. In addition motion transverse to the longitudinal axis of the watch stem is prevented by bent-down tabs of the leaf spring which span the watch stem in a direction transverse to the axis of the watch stem. Finally, precise positioning of the tab which seats in the grooves of the watch stem with respect to the axial direction is achieved by means of a bent-down tab at the free end of the leaf spring located in a notch in a member fastened to the base plate. Movement of the tab in an axial direction is prevented by the walls of the notch.

Accordingly, an object of the invention is precise positioning of a watch stem in an axial direction and in directions transverse to the axis.

Another object of the invention is precise positioning of a watch stern by means of grooves thereon and a precisely positioned leaf spring.

A further object of the invention is precise positioning of a watch stem by means of a minimum number of components and using a minimum amount of space.

Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.

The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWING For a fuller understanding of the invention, reference is had to the following description taken in connection with the accompanying drawing, in which:

FIG. 1 is an enlarged partial plan view of a watch stem positioning mechanism in accordance with the present invention;

FIG. 2 is a side view in partial cross section of the same mechanism; and

FIG. 3 is an end view in partial cross section of the same mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT watch stem 7 firmly against base plate 5 Motion of the watch stem 7 in a direction parallel to the base plate 5 and transverse to the stem axis is prevented by means of L-shaped tabs 10 and 11 which span watch stem 7.

Possible rotation of holding member 6 about screw 15 as a pivot is prevented by element 12, secured to base plate 5, and having a notch 13. L-shaped tab 14 at the end of holding member 6 is positioned in notch 13 and is constrained against motion parallel to the axis of the watch stem by the walls forming notch 13.

The holding mechanism of the present invention has the following advantages over the conventional construction:

I. The watch stem is precisely located in both radial and axial directions.

2. Variation in the distance traversed in moving from one groove position to the next is extremely small.

3. High precision in the manufacture of the components of the mechanism is not required and consequently the cost of manufacture is lowered.

4. The number of parts required is reduced.

5. The space required for the mechanism is reduced.

6. Since the entire mechanism can be placed on the surface of a plate (on that side on which bridges are fitted), it is unnecessary to reverse a watch during assembly. This factor is particularly important for automatic assembly.

7. The spring which provides the above advantages is essentially flat and is simple to manufacture.

8. The mechanism can be used for a calendar watch, for the lever of a chronograph and for adjusting the rate of a watch.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

What is claimed is:

I. In a watch, a mechanism for precise positioning of a movable watch stem, comprising a base plate, a watch stem mounted for axial and rotational movement on said base plate and having a plurality of grooves thereon, and a flexible spring member having an end and fixed proximate said end to said base plate and having a first tab for resilient engagement with a groove on said stern and for thereby locating said stem precisely in an axial direction and having second and third tabs positioned proximate said stem for fixing the position of said stem in a direction essentially parallel to said base plate and transverse to the longitudinal axis of said stem.

2. A mechanism as defined in claim 1, further comprising an element fixed to said base plate, said element having a notch and said flexible spring member having a fourth tab disposed between the walls of said notch, the walls of said notch constraining said fourth tab and thereby said spring member against motion in a direction parallel to the longitudinal axis of said stem. 

1. In a watch, a mechanism for precise positioning of a movable watch stem, comprising a base plate, a watch stem mounted for axial and rotational movement on said base plate and having a plurality of grooves thereon, and a flexible spring member having an end and fixed proximate said end to said base plate and having a first tab for resilient engagement with a groove on said stem and for thereby locating said stem precisely in an axial direction and having second and third tabs positioned proximate said stem for fixing the position of said stem in a direction essentially parallel to said base plate and transverse to the longitudinal axis of said stem.
 2. A mechanism as defined in claim 1, further comprising an element fixed to said base plate, said element having a notch and said flexible spring member having a fourth tab disposed between the walls of said notch, the walls of said notch constraining said fourth tab and thereby said spring member against motion in a direction parallel to the longitudinal axis of said stem. 